perf: remove unneeded entries from the ELI when it is downloaded

scripts/downloadEli.ts

@@ -0,0 +1,87 @@
+import Script from "./Script"
+import { Utils } from "../Utils"
+import { FeatureCollection } from "geojson"
+import fs from "fs"
+
+class DownloadEli extends Script {
+    constructor() {
+        super("Downloads a fresh copy of the editor layer index, removes all unnecessary data.")
+    }
+    async main(args: string[]): Promise<void> {
+        const url = "https://osmlab.github.io/editor-layer-index/imagery.geojson"
+        // Target should use '.json' instead of '.geojson', as the latter cannot be imported by the build systems
+        const target = args[0] ?? "assets/editor-layer-index.json"
+
+        const eli = <FeatureCollection>await Utils.downloadJson(url)
+        const keptLayers = []
+        console.log("Got", eli.features.length, "ELI-entries")
+        for (let layer of eli.features) {
+            const props = layer.properties
+
+            if (props.type === "bing") {
+                // A lot of work to implement - see https://github.com/pietervdvn/MapComplete/issues/648
+                continue
+            }
+
+            if (props.id === "MAPNIK") {
+                // Already added by default
+                continue
+            }
+
+            if (props.overlay) {
+                continue
+            }
+
+            if (props.url.toLowerCase().indexOf("apikey") > 0) {
+                continue
+            }
+
+            if (props.permission_url === "no") {
+                continue
+            }
+
+            if (props.max_zoom < 19) {
+                // We want users to zoom to level 19 when adding a point
+                // If they are on a layer which hasn't enough precision, they can not zoom far enough. This is confusing, so we don't use this layer
+                continue
+            }
+
+            if (props.name === undefined) {
+                console.warn("Editor layer index: name not defined on ", props)
+                continue
+            }
+
+            const keptKeys = [
+                "name",
+                "id",
+                "url",
+                "attribution",
+                "type",
+                "category",
+                "min_zoom",
+                "max_zoom",
+                "best",
+                "default",
+                "tile-size",
+            ]
+            layer.properties = {}
+            for (const keptKey of keptKeys) {
+                if (props[keptKey]) {
+                    layer.properties[keptKey] = props[keptKey]
+                }
+            }
+
+            layer = { properties: layer.properties, type: layer.type, geometry: layer.geometry }
+            keptLayers.push(layer)
+        }
+
+        const contents =
+            '{"type":"FeatureCollection",\n  "features": [\n' +
+            keptLayers.map((l) => JSON.stringify(l)).join(",\n") +
+            "\n]}"
+        fs.writeFileSync(target, contents, { encoding: "utf8" })
+        console.log("Written", keptLayers.length + ", entries to the ELI")
+    }
+}
+
+new DownloadEli().run()